Oil spill at the sea may occur by accident on ships or petroleum platforms or by transfer between such. Determination of the size and quality of an oil spill is a priority task for efficient oil pollution control, we refer to the Norwegian regulation “Regulation about conducting activities in the petroleum industry”, I cite:
§57. Remote Sensing of Acute Pollution
“The operator shall establish a remote sensing system which provides sufficient information to ensure that acute pollution from the installation is discovered quickly and mapped so as for the amount and distribution of the released [pollution] may be established. The remote sensing system shall be seen in the context of regional remote sensing plans as mentioned in this regulation §78.
According to the guideline text to the above paragraph it appears, among others, as follows:                By remote sensing is meant a system which, independently of visibility, light, and weather conditions, may discover and map the position, area, amount and properties of acute pollution.        In order for the remote sensing system shall discover acute pollution of significance, the area around the installation should regularly be remote sensed. This implies that the response time for remote sensing should not exceed the shortest expected drift time to vulnerable resources at the sea, at the sea surface or in the water column.”        
According to the “Norwegian Oil protection Association for Operating companies” (NOFO) the “Norwegian Climate- and Pollution Directorate” defines the response time down to 3 hours.
Present sensors are traditional X-band (9.5 GHz) navigation radars with a specially adapted signal and data processing and an infrared camera. Infrared cameras have their limitations at high levels of air humidity and bad visibility, such as fog, precipitation of rain and snow. Ordinary X-band radars have limitations in their detectability of oil on water at calm sea, i.e. wind speeds less than 3 m/s. Present X-band radars for this purpose have horizontally polarized emission and horizontally polarized receipt, so-called “HH” polarization.
Based on stricter requirements from the Norwegian Climate- and pollution Directorate with regard to the increased requirement on oil detectability and the strict response time requirement, there is a need for a radar with a range up to about 2000 m which is capable of determining both the size and thickness distribution of an oil spill under most weather conditions.